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35-493: The BRAS sits at the edge of an ISP's core network , and aggregates user sessions from the access network . It is at the BRAS that an ISP can inject policy management and IP quality of service (QoS). The specific tasks include: A DSLAM collects data traffic from multiple subscribers into a centralized point so that it can be transported to a switch or router over a Frame Relay, ATM, or Ethernet connection. The router provides

70-445: A hotspot service. Network topology describes the layout of interconnections between devices and network segments. At the data link layer and physical layer , a wide variety of LAN topologies have been used, including ring , bus , mesh and star . Simple LANs generally consist of cabling and one or more switches . A switch can be connected to a router , cable modem , or ADSL modem for Internet access. A LAN can include

105-610: A mesh topology that provided any-to-any connections among devices on the network. Many main service providers would have their own core/backbone networks that are interconnected. Some large enterprises have their own core/backbone network, which are typically connected to the public networks. Backbone networks create links that allow long-distance transmission, usually 10 to 100 miles, and in certain cases - up to 150 miles. This makes backbone network essential to providing long-haul wireless solutions to provide internet service , especially to remote areas. Core networks typically provided

140-514: A cluster or a single switch or router. The topology and architecture of a collapsed backbone is a star or a rooted tree . The main advantages of the collapsed backbone approach are However, the drawback of the collapsed backbone is that if the box housing the backbone is down or there are reachability problem to the central location, the entire network will crash. These problems can be minimized by having redundant backbone boxes as well as having secondary/backup backbone locations. There are

175-575: A few different types of backbones that are used for an enterprise-wide network. When organizations are looking for a very strong and trustworthy backbone they should choose a parallel backbone. This backbone is a variation of a collapsed backbone in that it uses a central node (connection point). Although, with a parallel backbone, it allows for duplicate connections when there is more than one router or switch . Each switch and router are connected by two cables. By having more than one cable connecting each device, it ensures network connectivity to any area of

210-573: A good indication of the situation. A number of experimental and early commercial LAN technologies were developed in the 1970s. Ethernet was developed at Xerox PARC between 1973 and 1974. Cambridge Ring was developed at Cambridge University starting in 1974. ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977. It had the first commercial installation in December 1977 at Chase Manhattan Bank in New York. In 1979,

245-513: A hierarchy. This kind of topology allows for simple expansion and limited capital outlay for growth, because more layers of devices can be added to existing layers. In a distributed backbone network, all of the devices that access the backbone share the transmission media, as every device connected to this network is sent all transmissions placed on that network. Distributed backbones, in all practicality, are in use by all large-scale networks. Applications in enterprise-wide scenarios confined to

280-429: A path for the exchange of information between different LANs or subnetworks . A backbone can tie together diverse networks in the same building, in different buildings in a campus environment, or over wide areas. Normally, the backbone's capacity is greater than the networks connected to it. A large corporation that has many locations may have a backbone network that ties all of the locations together, for example, if

315-485: A plethora of methods of sharing resources. Typically, each vendor would have its own type of network card, cabling, protocol, and network operating system . A solution appeared with the advent of Novell NetWare which provided even-handed support for dozens of competing card and cable types, and a much more sophisticated operating system than most of its competitors. Of the competitors to NetWare, only Banyan Vines had comparable technical strengths, but Banyan never gained

350-459: A secure base. 3Com produced 3+Share and Microsoft produced MS-Net . These then formed the basis for collaboration between Microsoft and 3Com to create a simple network operating system LAN Manager and its cousin, IBM's LAN Server . None of these enjoyed any lasting success; Netware dominated the personal computer LAN business from early after its introduction in 1983 until the mid-1990s when Microsoft introduced Windows NT . In 1983, TCP/IP

385-399: A server cluster needs to be accessed by different departments of a company that are located at different geographical locations. The pieces of the network connections (for example: Ethernet, wireless) that bring these departments together is often mentioned as network backbone. Network congestion is often taken into consideration while designing backbones. One example of a backbone network

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420-434: A single building are also practical, as certain connectivity devices can be assigned to certain floors or departments. Each floor or department possesses a LAN and a wiring closet with that workgroup's main hub or router connected to a bus-style network using backbone cabling. Another advantage of using a distributed backbone is the ability for network administrator to segregate workgroups for ease of management. There

455-439: A single cable in a daisy-chain fashion. A daisy chain is a group of connectivity devices linked together in a serial fashion. Hubs are often connected in this way to extend a network. However, hubs are not the only device that can be connected in a serial backbone. Gateways , routers , switches and bridges more commonly form part of the backbone. The serial backbone topology could be used for enterprise-wide networks, though it

490-495: A wide variety of other network devices such as firewalls , load balancers , and network intrusion detection . Advanced LANs are characterized by their use of redundant links with switches using the spanning tree protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and their ability to segregate traffic with VLANs . At the higher network layers, protocols such as NetBIOS , IPX/SPX , AppleTalk and others were once common, but

525-422: Is rarely implemented for that purpose. LAN A local area network ( LAN ) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger geographic distance, but also generally involves leased telecommunication circuits . Ethernet and Wi-Fi are

560-540: Is still the basis of most commercial LANs today. While optical fiber cable is common for links between network switches , use of fiber to the desktop is rare. In a wireless LAN , users have unrestricted movement within the coverage area. Wireless networks have become popular in residences and small businesses, because of their ease of installation. Most wireless LANs use Wi-Fi as wireless adapters are typically integrated into smartphones , tablet computers and laptops . Guests are often offered Internet access via

595-461: Is the Internet backbone . The theory, design principles, and first instantiation of the backbone network came from the telephone core network when traffic was purely voice. The core network was the central part of a telecommunications network that provided various services to customers who were connected by the access network . One of the main functions was to route telephone calls across

630-429: Is the possibility of single points of failure, referring to connectivity devices high in the series hierarchy. The distributed backbone must be designed to separate network traffic circulating on each individual LAN from the backbone network traffic by using access devices such as routers and bridges. A conventional backbone network spans distance to provide interconnectivity across multiple locations. In most cases,

665-722: The Electronic voting systems for the European Parliament was the first installation of a LAN connecting hundreds (420) of microprocessor-controlled voting terminals to a polling/selecting central unit with a multidrop bus with Master/slave (technology) arbitration. The development and proliferation of personal computers using the CP/M operating system in the late 1970s, and later DOS -based systems starting in 1981, meant that many sites grew to dozens or even hundreds of computers. The initial driving force for networking

700-404: The Internet protocol suite (TCP/IP) has prevailed as the standard of choice. LANs can maintain connections with other LANs via leased lines, leased services, or across the Internet using virtual private network technologies. Depending on how the connections are established and secured, and the distance involved, such linked LANs may also be classified as a metropolitan area network (MAN) or

735-551: The PSTN . Typically the term referred to the high capacity communication facilities that connect primary nodes. A core network provided paths for the exchange of information between different sub-networks . In the United States, local exchange core networks were linked by several competing interexchange networks ; in the rest of the world, the core network has been extended to national boundaries. Core networks usually had

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770-640: The United States. However, WWMCCS was superseded by the Global Command and Control System (GCCS) before that could happen. During the same period, Unix workstations were using TCP/IP networking. Although the workstation market segment is now much reduced, the technologies developed in the area continue to be influential on the Internet and in all forms of networking—and the TCP/IP protocol has replaced IPX , AppleTalk , NBF , and other protocols used by

805-439: The backbones are the links while the switching or routing functions are done by the equipment at each location. It is a distributed architecture. A collapsed backbone (also known as inverted backbone or backbone-in-a-box) is a type of backbone network architecture. In the case of a collapsed backbone, each location features a link back to a central location to be connected to the collapsed backbone. The collapsed backbone can be

840-672: The benches of the European Parliament Hemicycles in Strasbourg and Luxembourg. Early Ethernet ( 10BASE-5 and 10BASE-2 ) used coaxial cable . Shielded twisted pair was used in IBM's Token Ring LAN implementation. In 1984, StarLAN showed the potential of simple unshielded twisted pair by using category 3 cable —the same cable used for telephone systems. This led to the development of 10BASE-T (and its twisted-pair successors ) and structured cabling which

875-628: The early PC LANs. Econet was Acorn Computers's low-cost local area network system, intended for use by schools and small businesses. It was first developed for the Acorn Atom and Acorn System 2 / 3 / 4 computers in 1981. In the 1980s, several token ring network implementations for LANs were developed. IBM released their own implementation of token ring in 1985, It ran at 4  Mbit/s . IBM claimed that their token ring systems were superior to Ethernet, especially under load, but these claims were debated. IBM's implementation of token ring

910-447: The enterprise-wide network. Parallel backbones are more expensive than other backbone networks because they require more cabling than the other network topologies . Although this can be a major factor when deciding which enterprise-wide topology to use, the expense of it makes up for the efficiency it creates by adding increased performance and fault tolerance . Most organizations use parallel backbones when there are critical devices on

945-449: The following functionality: Physically, one or more of these logical functionalities may simultaneously exist in a given core network node. Besides the above-mentioned functionalities, the following also formed part of a telecommunications core network: A distributed backbone is a backbone network that consists of a number of connectivity devices connected to a series of central connectivity devices, such as hubs, switches, or routers, in

980-531: The logical network termination. Common link access methods include PPP over Ethernet ( PPPoE ), PPP over ATM ( PPPoA ) encapsulated sessions, bridged Ethernet over ATM or Frame Relay (RFC 1483/RFC 1490), or just plain Ethernet. In the case of ATM or Frame Relay based access, individual subscribers are identified by Virtual Circuit IDs. Subscribers connected over Ethernet-based remote access devices are usually identified by VLAN IDs or MPLS tags. By acting as

1015-432: The network termination point, the BRAS is responsible for assigning network parameters such as IP addresses to the clients. The BRAS is also the first IP hop from the client to the Internet. The BRAS is also the interface to authentication, authorization and accounting systems (see RADIUS ). Core network A backbone or core network is a part of a computer network which interconnects networks, providing

1050-411: The network. For example, if there is important data, such as payroll , that should be accessed at all times by multiple departments, then your organization should choose to implement a parallel backbone to make sure that the connectivity is never lost. A serial backbone is the simplest kind of backbone network. Serial backbones consist of two or more internet working devices connected to each other by

1085-518: The two most common technologies in use for local area networks. Historical network technologies include ARCNET , Token Ring and AppleTalk . The increasing demand and usage of computers in universities and research labs in the late 1960s generated the need to provide high-speed interconnections between computer systems. A 1970 report from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gave

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1120-522: Was a relatively high-speed choice of that era, with speeds such as 100 Mbit/s. By 1994, vendors included Cisco Systems , National Semiconductor , Network Peripherals, SysKonnect (acquired by Marvell Technology Group ), and 3Com . FDDI installations have largely been replaced by Ethernet deployments. In 1979, the Electronic voting systems for the European Parliament was using 10 kilometers of simple unshielded twisted pair category 3 cable —the same cable used for telephone systems—installed inside

1155-442: Was first shown capable of supporting actual defense department applications on a Defense Communication Agency LAN testbed located at Reston, Virginia. The TCP/IP-based LAN successfully supported Telnet , FTP , and a Defense Department teleconferencing application. This demonstrated the feasibility of employing TCP/IP LANs to interconnect Worldwide Military Command and Control System (WWMCCS) computers at command centers throughout

1190-624: Was the basis of the IEEE 802.5 standard. A 16 Mbit/s version of Token Ring was standardized by the 802.5 working group in 1989. IBM had market dominance over Token Ring, for example, in 1990, IBM equipment was the most widely used for Token Ring networks. Fiber Distributed Data Interface (FDDI), a LAN standard, was considered an attractive campus backbone network technology in the early to mid 1990s since existing Ethernet networks only offered 10 Mbit/s data rates and Token Ring networks only offered 4 Mbit/s or 16 Mbit/s rates. Thus it

1225-450: Was to share storage and printers , both of which were expensive at the time. There was much enthusiasm for the concept, and for several years, from about 1983 onward, computer industry pundits habitually declared the coming year to be, "The year of the LAN". In practice, the concept was marred by the proliferation of incompatible physical layer and network protocol implementations, and

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